1. Field of the Invention
The invention concerns a device for measuring thermal expansion, in particular thermal expansion of a ferrule adapted to receive an optical fiber.
2. Description of the Prior Art
An optical fiber connector ferrule has a highly accurate cylindrical exterior contour and a highly accurate axial aperture on the ferrule axis. The aperture diameter, typically 125 microns, is matched to the exterior diameter of an optical fiber complete with its optical cladding. The exterior contour of any such ferrule must be precisely cylindrical, with an accuracy of better than 1 micron. The nominal diameter of the exterior contour being 2 500 microns for a standard optical fiber connector ferrule, the accuracy required means that thermal expansion measurements have to be carried out to determine the behavior of the component.
In the case of a plastics material ferrule, measuring the diameter using mechanical feelers has the drawback of being poorly reproducible since the impact of the feelers on the surface of the ferrule is likely to crush the latter by an amount in the order of a few microns, so that the measurement is insufficiently accurate.
It is known to measure the size of a sample using a laser beam and a base member incorporating a reference groove, usually of V-shape, in which the sample to be measured is placed.
An object of the present invention is a thermal expansion measurement device offering high accuracy compatible with that required for measurement of optical fiber connector ferrules.